1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more specifically, to a method of manufacturing a semiconductor device including an in-layer lens in a pixel portion.
2. Description of the Related Art
As a semiconductor device, for example, there has been known a solid-state image pick-up device such as a CCD described in JP-A-2002-246578 and JP-A-2003-7988, for example. In the solid-state image pick-up device, a pixel portion of a semiconductor substrate includes a photoelectric converting portion such as a photodiode and an electric charge transfer portion for transferring an electric charge generated in the photoelectric converting portion, and a microlens is formed on a surface of the pixel portion. Moreover, some solid-state image pick-up devices have such a structure that a predetermined film (for example, a passivation film) in a layer of the pixel portion is set to be an in-layer lens in which a region on the photoelectric converting portion is formed to take a shape of a lens in order to reliably receive a light collected on the microlens by the photoelectric converting portion and to enhance a light sensitivity.
In the case in which a downward convex in-layer lens is provided on an optical layer of a solid-state image pick-up device such as a CCD, a thickness of the downward convex in-layer lens is controlled by using an etch-back method in order to enhance a degree of flatness of a surface of the downward convex in-layer lens layer or to regulate a distance to a microlens in an uppermost part. At this time, there is a fear that the following drawbacks might be caused.
FIG. 4 is a typical sectional view for explaining a part of a process for manufacturing the solid-state image pick-up device. In FIG. 4, a semiconductor substrate 1 is provided with a peripheral circuit portion 1a having a metal wiring portion 3 formed thereon and a pixel portion 1b having a photoelectric converting portion (not shown) and an electric charge transfer electrode 2 formed thereon, and an in-layer lens layer 5 is formed in the pixel portion 1b. The in-layer lens layer 5 is applied onto a whole surface of the semiconductor substrate including the peripheral circuit portion 1a and the pixel portion 1b and is then subjected to a surface treatment to have a predetermined thickness by an etch-back method. At this time, the in-layer lens layer 5 is wholly thinned by the etch-back method. As a result, there is a fear that an upper part of the metal wiring portion 3 covered with the in-layer lens layer 5 in the peripheral circuit portion 1a might be exposed to damage the metal wiring portion 3.
In consideration of the circumstances, it is an object of the invention to provide a method of manufacturing a semiconductor device and the semiconductor device which can prevent a metal wiring portion of a peripheral circuit portion from being damaged when forming an in-layer lens in a pixel portion.